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Hello,
I have an extractor fan in the bathroom ceiling that connects to a roof tile vent.
Discovered yesterday it was full of water in the places where the ducting had flat bends.
Done some googling and while I now know that it should be insulated and preferably not ridged to minimise condensation, I can't find an answer on how it should run.
Should extractor duct run as straight as possible between ceiling and roof vent - e.g near verticle in my case.
That would make sense, but is there then a risk that any condensation would run back down and into the fan?
Pretty sure someone on here will have a definite answer. Cheers!
I'd say you want it to run back to the fan. The only other option is sitting in the pipe which isn't great. The ideal would be for it to run out the vent but that is impossible for a tile vent. If it is straight and short there won't be much condensation at all.
Condensation trap.
I also run my fan for at least 20mins afterwards thinking it will keep blowing air through and minimise moist air in the duct.
Thanks both - our fan runs a good long time after turned off and so with a straight run the condensation should be minimal.
But if I'm up in the loft re-doing the ducting, it's not going to hurt putting in a condensation trap - just googled those, wasn't aware of them.
Stops water going back down into the fan, but then needs somewhere to drain off any water that does collect, which could be tricky.
Yes it could be tricky, also will need to be insulated to stop it potentially freezing too.
Stops water going back down into the fan
Is that a problem? They are pretty moisture resistant. I suppose the only issue is drips. Mine is over the shower so fine
Not fussed about water dripping back down, as it is over the shower.
Was just wondering about damage to the fan of water dripping down through it regularly - but guess they're designed to cope with moisture after all and it's going to be pretty negligble amount of water.
We had a fan blow (fail) in our old house which I think was due to condensation dripping back down.
I don't think they are particularly well sealed against moisture.
I ended up lagging the pipe with tons of insulation, which solved the problem. We made the pipe as straight as possible to directly between the fan & the vent.
Thanks stumpy - once I have it straight then it's only short, so plenty of lagging will be easy.
Ironically, in investigating the problem it looks like I've blown the fan anyway.
There was so much water gathered in the duct that when I lifted it up it sent about a pint of water straight down through the fan - doh!
So could be looking at new fan and new ducting.
We had a fan blow (fail) in our old house which I think was due to condensation dripping back down.
I don’t think they are particularly well sealed against moisture.
We've had exactly this. Unfortunately rather than a tile vent, we have a very long flue sticking out of the roof upwards.
We don't have access to the roof void either (without breaking out loads of plasterboard) or roof access (as it would be via the neighbour's garden which is about 30ft below the roof line!).
There's no access to fit a drain for any condensation trap either - has anyone used anything like this before?
"small reservoir that condensation can collect in and then evaporate during the day when the fan is not in use"
That could be an issue over winter though?
How long is the ducting run going to be? Mine goes pretty much vertically up from bathroom ceiling to roof vent, probably 5-6ft of ducting - I asked the plumber if it needed a condensate trap and he was adamant it wouldn't for such a short run and he'd only usually fit one if bends + long run was involved.
I redid ours in November. Ceiling mount fan changed to an inline fan in the loft. The duct was such a short run that rigid ducting was the cheaper option. You couldn't seem to buy flexible insulated ducts in short lengths (I think 10 metres was £30). Most of the duct is horizontal and under the insulation in the loft. It then turns 90 deg vertically, though the fan and out of a tile vent. The vertical section is uninsulated.
A condensation trap was less than £10 so I fitted one above the fan, below the vertical section. The run off currently goes into a plastic bottle though. I plan to leave it like this and see how much condensation is gathered (might check this weekend). If there is any, then I'll first insulate the vertical duct and leave it again. Should there still be condensate collected, I'll look at plumbing in the run off.
Overall I think it will ok, as the vertical run is so short, but for the sake of £10 I can be sure.